Ecological Niches - B4.2.1-4.2.6

Ecological niches are multidimensional spaces which include:

• Habitat

• Activity patterns

• Use of resources

• Interactions with other species

Zone of Tolerance

• includes abiotic and biotic variables that influence growth survival, reproduction

Abiotic Variables

Non-living components of an ecosystem

• e.g. light intensity, temperature, humidity, pH, salinity, oxygen levels

Biotic Variables

Living components of an ecosystem in intraspecific and interspecific relationships

• pollination

• seed dispersal

Generalists

• have broad ecological niches

• can thrive in a wide range of environmental conditions, with a varied diet

• less likely to go extinct

• advantage when conditions change

  • e.g. raccoons

Specialists

• narrow ecological niches

• thrive in specific environmental conditions with a limited diet

• more likely to become extinct

• advantage when conditions remain constant

  • e.g. koalas

Method of respiration

How a species exchanges gases based on their ecological niche

Obligate aerobes

• need a continuous supply of oxygen

• aerobic respiration

• need to in an oxic environment

  • e.g. tuberculosis

Obligate anaerobes

• inhibited/killed under oxygen

• anaerobic respiration

• some rely on fermentation

Facultative anaerobes

• oxygen when available

• e.g. E.Coli/Bacteria

Winogradsky colum

• compares oxygen requirements of microbes

• miniature ecosystem made of mud and water mixed with carbon sources and sulfur sources in a clear cylinder

• once it’s sealed, the enrichment culture is incubated under sunlight, resulting in aerobic and anaerobic gradients over time

• After a few weeks, microbes create colour bands as ecological niches

photosynthetic autotrophs (Examples)

• Terrestrial and aquatic plants

• Single-celled algae and multicellular seaweeds (e.g. pondweed)

• Photosynthetic prokaryotes (e.g. cyanobacteria)

Why doesn’t photosynthesis occur in archaea (obligate anaerobes)?

they lack chlorophyll

Oxygenation

• Cellular respiration

• Ozone layer

Carbon fixation

• organic molecules

Energy Transfer

• light energy > chemical energy

What does all animals being heterotrophic indicate?

They are incapable of synthesizing their own food the sustain themselves, so they must find various ways to fulfill their needs.

Holozoic nutrition

Whole pieces of food are swallowed before being fully digested.

Heterotrophs

• organisms that obtain energy through other animals

• Consumers, e.g. animals, fungi

Autotrophs

• Obtain energy through photosynthesis

• Producers (plants)

Five stages of holozoic nutrition

1. Ingestion

2. Digestion

3. Absorption

4. Assimilation

5. Egestion

Ingestion

• Process of taking food through the mouth

• Food is mechanically broken down with the teeth and chemically broken down with the salivary amylase

Mastication

Preparation of food into bolus

Digestion

• Prior to absorption, polysaccharides, proteins and lipids must be digested

  • larger molecules > smaller molecules by enzymes

• Amylase breaks down carbs

• Protease breaks down proteins

• Lipase breaks down lipids

Absorption

Process of absorbing nutrients into the bloodstream to sustain life, allowing organisms to carry out necessary functions

by mechanisms of:

• active transport

• facilitated diffusion

• Lymphatic system

Assimilation

Process by which absorbed molecules are integrated into the body within tissues. These molecules can then be used for growth, repair, and energy production

Egestion

Metabolic process of removing undigested material from the end of the digestive tract (not excretion)

Mixotrophs

Organisms that are not exclusively autotrophic or heterotrophic. They have the ability to use both modes of nutrition.

Facultative mixotrophs

• Can be entirely autotrophic, heterotrophic, or both

Obligate mixotrophs

• Must use autotrophic AND heterotrophic modes

Saprotrophs

• Secrete digestive enzymes externally, then absorb the products

• Also known as decomposers because they break down carbon compounds in dead organic matter and release elements such as nitrogen to be recycled in the ecosystem

Detritivores

organisms which feed on dead matter via internal ingestion (e.g. earthworms)